Field of the Invention
The present invention generally relates to microelectronic or micromechanical structures. In particular, the invention relates to transferring, in one exposure, a single-mask feature to form two features on an underlying material. Specifically, a doubled walled structure (i.e. an opening flanked by adjacent openings) is formed. Advantageously, the openings may be sub-resolution openings.
Description of Related Art
In fabricating microelectronic of micromechanical devices, structures are formed by overlying a photoresist above a material to be patterned. A mask having a pattern is then used to expose the photoresist to electromagnetic radiation (light). The exposed photoresist is developed so that the pattern from the mask transfers to the photoresist. The patterned photoresist now becomes the resist mask through which the underlying material is etched, thus transferring the pattern to the underlying material. The resist is removed resulting in a patterned material. The pattern in the material matches the pattern of the mask, meaning if there are three features/shapes on the mask, then three are transferred to the material. Furthermore, the feature size that can be transferred to the material is limited by the resolution of the optical system used to transfer the pattern from the mask to the resist.
However, the present invention allows for patterning of multiple features on a material despite the mask having a single feature. Furthermore, the present invention allows for transfer of sub-resolution feature(s) to the underlying material.